Electroplating method and electroplated articles



Patented Dec. 2 2 1925.

Io Drawing.

- UNITED STAT'ES PATENT OFFICE.

ROBERT-JAY SHOEMAKEB, OF CHICAGO, ILLINOIS.

ELECTBOPLATING METHOD AND EL ECIBOPLATED ARTICLES.

To all whom it may conccm Be itknown that I, ROBERT J. SHOE MAKER, acitizen of the United States, residing at Chicago, in the county of Cookand State of Illinois, have invented certain new and useful Improvementsin Electroplating Methods and Electroplated Articles, of which thefollowing is a specification.

My invention relates to methods of electroplating, and more especiallyto the electroplating of iron or steel articles such, for example, asboiler tubes, sheets, pipes, castings and forgings. The invention is ofparticular utility in electroplatingiron or steel articles with leadinasmuch as it provides,

l electrolysis iron or steel articles (and hereafter throughout thespecification and claims I- shall use the term iron as coveringbothspecies), but so far as I .am aware, it has not been found possibleheretofore to carryout this operation satisfactorily. If the surface tobe covered is slightly greasy or has any scale adhering thereto, even ofa microscopic character, the uniformity, density and ho-.

. mogeneity of the lead plating will be affected. It is diflicult if notimpossible even by pickling the article in acid to clean the" surface tobe plated sufliciently to make the coating even, non-porous anduniformly adherent. There is also a tendency of the lead to deposit instreaks, that is, in irregular strips with intervening spaces lessthickly covered. The reason forthis is. not fully understood but thephenomenon'is recognized-b those who have made experiments along t isline.

The lead will also deposit more readily and densely on surfaces that aresmooth than on rough surfaces so that variations in the character of theiron surface due to inequali- -.ties in rolling and other like causes,affect the character of the lead deposited by electrolysis on suchsurface.

There is also a tendency, during the eleclyj to blister.

Application filed October 1, 1928: semi No. 865,951.

trolytic operation, for the lead to tree out from the article andeventually produce a short circuit. It .does not seem possible toprevent treeing even with mechanical agitation.

Moreover, the lead coating does not adhere to the iron as firmly as isdesired. An electro-plated lead boiler tube, for example, if boiled inacids commonly used for testing these articles as to theircorrosibility, is like- Portions of the plating are loosened from theiron so as to be easily rubbed off.

* Finally, it has not been found possible so 4 far as I am aware, tocover an iron wit a lead plating produced electrolytically which will bedense enough to prevent corrosion of the iron through the plating. Thisis also true of iron bodies -electro-plated with tin, nickel and copper.

The primary objects of my invention are,

therefore: first, to provide a practical method of. electro-plating ironarticles with lead and, second, an improvement in the methods ofelectro-plating iron bodies, regardless of the plating metal used, toprevent the rusting through of the iron.

Other less important objects will be re ferred to inconnection with thefollowing.

description of the preferred manner of practicing the invention.

The method will-be described first in connection with lead plating. N

(a) The body or article to be plated is first pickled and cleaned in theusual Way with sulphuric acid or some other suitable cleansing acid. Itmay afterward be washed with water but that is not necessary. 4

(b) 7 his then immersed in a dilute solution of a copper salt capable ofreacting by substitution with the iron, which solution preferablycontains an inert agent serving to retard the corrosive action of thesolution on the iron. The solution is prefer ably composed of thefollowing ingredients: 100

Copper sulphate, 2 parts (by weight);

water, parts; glue, 1 part; commercial sulphuric acid, 1 part. Copperchloride may be used'in place of cop er sulphate. The

function of the glue is to s ow down the corrovided care is taken thatthe articles should 0 Otherwise the iron would. be too not remain in thebath too long. The reaction is in the sense of the following equations,depending upon whether copper sulphate or copper chloride is used:

This treatment covers the article with a thin coating of copper.

(c) The article is then immersed in a Cu-l-HgGhzCuCh-l-Hgl A film ofmercury is formed over the copper coating, the mercury amalgamatin'gwith the copper. The effect seems to be to make the cop er adhere morefirmly to the iron and-to 211 the pores of the copper coating, which isrelatively porous,.so that a stratum is provided over the iron basewhich is very dense, smooth and of uniform character.

Instead of using the solution of mercury salt for producing the mercuryfilm over the copper coating, metallic mercury might be rubbed on thecopper coating. The operation, however, is diflicult and expensive.

((1) Assuming that the article has first been copper coated and thentreated 'with the mercury salt solution, it is then washed to remove theadherent chloride.

(6) The next step is the electroplating operationwhich may be carried onwith the use of any suitable electrolyte, such as lead silico-fluorideor, more desirable on account of economy, lead acetateJ Using leadacetate, the solution is preferably as follows:

Lead acetate, 10 parts (by Weight) commercial lime acetate, 10 parts;acetic acid, 1 part; water, 100 parts.

The electrolyte is kept in slow agitation by means of a pumporcompressed air during the process. The function of the lime acetate,in place of which ammonium acetate or sodium-acetate may be used, isprimarily to reduce internal resistance. Incidentally the. organicimpurity,'to-wit, compounds of pyroligneous acid, serve to preventtreeing. The current flow should be approximately one ampere per squarefoot of surface plated and the. potential from four to six volts.

' Metallic lead is used as a positive pole.

It will be understood. that in the electroplating of articles withmetals other than lead, thepreparation of the article for treatneeaesament in the electrolytic cell would be the same as describedin steps (a)and The operation of copper coating described as step (6) maybe used toadvantage without subsequent step (c) a copper electroplating operationprecedent to immersion of the article in the electrolytic cell. In thiscase the solution should be strengthened to containabout 10% coppersalt.

Steps (1)) and (6), whereby the body is covered with a coatingconsisting. of an amalgam of copper and mercury, may be advantageouslyused in preparing billets for cold drawing into pipes, tubes, and thelike.

The coatingprovides an excellent metallic lubricant. which, lfnecessary,may be removed by pickling in case it is necessary to anneal. the billetbetween draws.

The operations described as steps (a) and (d) might be usedadvantageously as a pretreatment in the lead tin or nickel plating ofcopper, brass or bronze articles.

I claim:

1. Improvement in the method-of electroplating iron articles whichconsists in covermg the surface of the article to be plated with apermanently adherent film of mercury and a metal with which mercury willamalgamate and thereafter electro-plating said surface.

2. Improvement in the method of electro-, plating iron articles whichconsists in coating the surface of the article to be plated with copperand covering the cop ered surface with a film of mercury prior to theelectro-plating operation.

Method of electro-plating iron articles which consists in immersing thearticle in a solution of a copper salt capable of reacting bysubstitution with the iron to coat the article with copper, covering thecoppered surface with a film of mercury, and then electro-plating themercury covered surface.

4 Method of electro-plating iron articles which consists in immersingthe, article in a solution of a copper salt capable of reacting bysubstitution with the iron to coat the same with copper, immersing thearticle in a solution of a mercury salt capable of reacting with thecopper to produce an amalgamation of metallic mercury with the coppercoating, and then electro-plating the' solution of copper salt capableof reacting by substitution with the iron and containing an agent forretardin the corrosive action of the solution on the non to coat thearticle with copper, immersing the article in a solution of a mercurysalt capable of reacting cle which consists in immersing the article inan aciduated solution of copper sulphate or .itsequivalent to produce areaction in the sense of the equation Fe-|-CuSO,=FeSO,+Ou;

immersing the article in a solution of mercuric chloride or 1tsequivalent to produce a reaction 1n the sense of the equatlon I and thenelectro-plating the article.

8. Method of electro-plating an iron arti-.

cle which consists in immersmg the article in an acidulated solution ofcopper sulphate or its equivalent, and containing glue, to

' produce a reaction in the senseof the equaimmersing-the-article in asolution of mercur1c chloride or its equivalent to produce a retardedreaction in the sense of the equa-.

tion 7 p v r Cu+HgCl =CuCl +I-I ,g, and then electro-plating thearticle.

9. Improvement in the method of electroplating iron articles with leadwhich consists in coating the surface of the article to e be plated withcopper and covering the coppered surface with a film of mercury prior tothe electro-plating operation.

10. Method of electro-plating iron arti-- cles with lead which consistsin immersing the article in a solution of a copper salt capable ofreacting by tsubstitution with'the iron to coat the article with copper,covering the coppered surface with a film of mercury,

- and then electro-plating the mercury covered surface. i

11. Method of electro-plating iron articles with-lead which consists inimmersing the article in a solution of a copper salt capa-- ble ofreacting by substitution with the iron to coat the same with copper,immersing the article in a solution of a mercury salt capable ofreacting with the copper to produce an amalgamation of metallic mercurywith the copper coating, and then electro-plating the surface sotreated.

12. Method of electroplatingv iron arti-' cles with lead which consistsin immersing the article in a solution of a copper salt iron andcontaining an agent for retarding the corrosive action of the solutionon the iron to coat the article with copper, covering the copperedsurface with a film of mercury, and then electro-plating the mer-icurycovered surface. p

13. Method of electro-plating iron articles with lead which consists inimmersing" the article in a solution of copperjsalt capable of reactingby substitution with the iron and containing an agent for retarding thecorrosive action of the solution on the iron to coat the article withcopper, immersing the article in a solution of a mercury salt capable ofreacting by substitution with the copper to produce an amalgam ofmetallic mercury with the copper coating, and then electro-plating thesurface so treated.

14. Method of electro-plating an iron article with lead which consistsin immersing the article in an acidulated solution of ,copper sulphateor its equivalent immersing the article in a solution of mercuricchloride or its equivalent and then electro-platingthe article.- 1 v-15. 'Method of electro-plating an iron article with lead, whichconsists in immersing the article in an acidulated solution of coppersulphate or its e uivalent, and containing glue, immersingt e article ina solution of mercuricchloride or its equivalent and thenelectro-plating' the article.

16. Method of producing a metal coating oniron articles which comprisestreating the article with a solution of copper salt capable of reactingby substitution with the iron and containing a retarding agent to slowthe corrosive action of the copper salt solution on the iron.

17. Method of producing a metallic coating on iron articles whichcomprises treating the article with a solution of copper sulphate or itsequivalent containing glue to retard the corrosive action of thesolution on the iron. a

18. Method of producin a metallic coating on iron articles whiccomprises..first covering the article with a coating of copper and thencovering the copper surface with mercury.

. 1.9. Method ing on iron articles which comprises treating the articlewith a solution of a copper s'alt capable of reacting by substitutionwith the iron and then treating the coppered surface with a solution ofa mercury salt capable of a substitution reaction with the coppercoating. 20. Method of producing a metallic coat mg on iron articleswhich comprises treating the article with a solution of a copper salt ofproducing a metallic coatcapable of reacting by substitution with the acapable of reacting by substitution with the iron and containing anagent to retard the corrosive action of the copper salt solution I onthe iron, *and then treating the coppered surface With a solution of amercury salt capable of 'a substitution reaction with the coppercoating.

21. Improvement in the method of electroplating which consists incovering the surface to beelectroplated with acopper coating andcovering the copper coating with a film of mercury.

22. Method of electroplating which compriees dissolving in theelectrolyte a soluing a stratum of mercury amalgamated with copper. I

24:. An electroplated iron article having between the iron surface andthe electroplatr ing first a coat of copper in contact with the iron andover the copper a' film. of mercury.

25/13 lead plated iron article having between the surface of the ironand the lead underthe electroplating 'a coating of copper and over thecopper a film of mercury.

ROBERT JAY sHoEMAKEn

